Preface: The formation of river-ice changes the flow distribution in rivers and streams, alters habitat availability, reduces light penetration, and can create a barrier between the aquatic environment and the atmosphere. This session is intended to explore how the formation, growth and breakup of river ice affect river systems and the species that live in them. Topics: • Winter and freshet hydrology of ice-affected rivers and streams • Biochemistry of ice-affected rivers • Winter habitat and refugia (of aquatic and semi-aquatic species) in ice-affected river systems • Heat transfer and freeze-up processes • Stream restoration in Cold Regions